Multi-range hoist system



Feb. 19, 1963 c. H. ZWEIFEL' ETAL 3078405 MULTI-RANGE HQIST SYSTEM Filed Ost. 16, 1956 s Sheets-Sheet 1 Feb. 193 1963 c. H. ZWEIFEL ETAL 3073405 MULTI-RANGE no:sw SYSTEM Filed Ost. 16, 1956 .Fz'g. 2

6 Sheets-Sheet 2 %|HIE Feb. 19, 1963 c. H. ZWEIFEL ETAL 3 MULTI-RANGE HOIST SYSTEM Filed Ost. 16, 1956 6 Sheets-Sheet 3 Feb. 19, 1963 c. H. ZWEIFEL ETAL 3O78406 MULTI-RANGE I-IOIST SYSTEM Filed Ost. 16, 1956 5 Sheets-Sheet 4 1963 c. H. ZWEIFEL ETL 3073406 MULTI-RANGE HOIST SYSTEM 6 Sheecs-Sheet 6 Filed 001:. 16 1956 United States Patent fi?ice 378,4% Pateeied Feb. 19, E53

3(978,486 MUL'iE-RANGE' HUHS'II SYSTEM Charles H. Zweifel, Oakiand, Marine S. Runde], Menin Park, am]! Robert C. Van Schaacia, San Francisco, Caiif.; said Zweifel am! seid Runde! assigners, by aii1rect anti mesne assignmexzais, to Paciiie (least Engineering Company, Aiameda, Caiif., a corgmzrzatiun 055 Califurnia, and said Van Schaack nssignmr to "Ehe Remis A!iis Com pany, Miiwankee, Wis., a comomtinn ef Wisconsin Fi!ed (Bei. 16, 1956, Sei. Neu. 616,274 Claims. (CH. 318-205) 0m invention relates to machinery involving hoisting equip-ment and more particuiarly to a system involving equipment such as cranes cf all types.

It is quite often necessary, as in the case of power hause er turbine deck cranes, to handle, at infrequent intervals, hezwy Ioads requiring precise handling and accurate control, thus necessitating movement of such heavy loadg at relatively IG'W speeds. In addition, on more frequent occasions, as for general servicing and maintenance, lighter loads are required to be handled at higher speeds. Such handlin-g of heavy loads and light ioa-ds is conventionally accomplished in the p1ior art by the installation anti use of two separate and independent sets of hoisting equipment, necessarily entailing for the heavy loads, a heavy load hook and associated load blocks, hoist -drums bearings, gear reducers, automatic safety braking devices, motors, electric brakes, controliers, etc., and for the light Ioads, an auxiliary or light 1oad hook Wit-h corresponding associated equipment.

As a result of having two independent sets cf hoist equipment, the first cost, installation, maintenance, and requirecl operating spares are excessive for the results obtained, particularly inasrnuch as the heavy duty equipment, as previously mentioned, is utilized but infrequently, While approxirnately 75% to 80% of all loads are handled by the lighter duty equipment.

Among the objects of the present invention a1'e:

(l) T0 provide a novel and improved system for hoist equipment;

(2) T0 provide a novel and improved system for hoist equipment, capable of operation over a plurality of loadspeed ranges;

(3) T0 provide a novel and improved system for hoist equipment utilizing alternating current or direct current power sources;

(4) T0 provide a novel and improved system for hoist equipment which is essentially foolproof in operation.

Additional objects of our invention will 'be brought out in the following description of a preferred em=bodiment of the same, taken in conjunction wit-h the accompanying drawiugs, where,

FIGURES 1 through 6 are component portions cf the c0mplete system embodying the features of the present invention, and utilizing alphabetical symbols to identify eonnecting leads.

Referring to the drawings of such system, lifted und lowered by means of a motor 1 operating hrough conventional type hoist mechanism 3 which may invclve a cable drum 5, suitaole sheaves 7, 9, etc. whi ch in t .1rn support a ioad hook 11. The loa-d motor and hoist. mechanism an: designed to handle the maximum ioad Wifl1 the motor operating at base speed and belo-w, and With the motor capable of functioning at higher speeds for lighter loads. Base speed is defined as the speed of the -motor when rated armature and field Voltages are applied.

'Fhe 10ad motor is of the direct current type and is provided wibh a series field winding 13 and a separately excited field Winding 15, the circuit of the series field winding including a heavy load current sensitive relay 17, a series resistor 13, a light load current sensitive reloads are lay 19, one winding 21 of a dual Winding relay 23, and one winding 25 of a secon-d dual winding relay 27. The series resistor 18 and relay 19 are adapted to he shunted b a resistor 29 through a pair cf normally open contacts 31.

Armature voltage to the motor is derived from the output of a direct current generator 33 Whose armature is mechanically driven by an ahernating current drive motor 35 adapted for operation from a three phase ower line 36. The generator like the ioad motor, is provided with a series field 37 and a separately excited field 3-9.

One side of ehe generator is connectable through the generator series field circuit, the motor series field circuit, including the relay 17, resistor ES, relay 19, and relay Windings 21 anal 25, to one brush of the motor anmature through a nor-mally open pair of contacts 49 011 the relay 43, and to the other brush throug h another normally open pair 013 -contacts 51 011 the relay 47. The other side of she generator is connectable directly to one brush of the motor through a normally open pair of con tacts 41 of a re1ay 43, and to die opposite brush of the motor through a normally opex1 pair of contacts 51 011 the relay 47.

The two pairs cf contacfs of each relay heing associated with opposite brushes of the motor, the energization of one of Ehe relays such as relay 43 will determine ro tation 0f bhe motor in one direction, such as in the direction of lift, w-hile the energization of the other relay will reverse the direction cf rotation for lowering a ioad.

Direct current excitation to the separately excited motor field 15 is derived from one phase of the three phase power line 36, as by means of a step down transformer 55 When the line voltage is higher than desired for obtaining field excitation. The transformer secondary 57 is connected ac-ross two corners of a full wave rectifier 59, the other twocorners being connected t0 the separately excited field circuit Which includes a current sensitive re1ay 61, a field resistor 63, the field Winding 15, normally open contacts 157, a series of adjustable field resistors 65, 67, 69 and 71, and the second Winding 73 cf the dual Winding relay 23.

Bach of the field resistors 65, 67, 69 and '71, is shunted by a pair of normally clesed relay contacts 79, 81, 33, and respectively. With all of resistors 67 threugh 71 shunted out, and With rated voltage applied to the armeture of the motor, the motor is designed to function at base speed. By weakening the field of the motor, as by cutting in one or more 0f the resistors, the speed of the motor may be increased above its base speed.

Direct current excitation to the separately excited generator field 39 is also derived through the step-dovvn transformer 53 in this instance from a lower voltage point 87 011 the secondary of such transformer, the output of Which is rectified through a full Wave rectifier 89 and applied to the generator fie1d through the ciosing of either of two pairs of normally open contacts 91 and 93.

In each lead to the separately excited field winding 01" the generator is a power Winding 95, such Windings sonstituting components of a magnetic amplifier for C011- trolling the voltage generated by the generator for application to the armature of the n1otor. For generating the rated voltage of the generator, these power Windings are operated at about saturation whereby the impedance is at a minimum and excitation of the generator field 1's at a maxirnum.

The function of a magnetic amplifier is to provide means for increasing the impedance of these windings to thereby decrease the field excitation and correspondingly decrease the voltage generated and applied to the armature of the load motor. In Lhis manner, the speed of the moror can be decreased from its base speed to a srnall fractional value thereof.

Such a magnetic arr1plifier includes the aforemcntioned power windings and a control winding 97 mountcd on a cornmon core f magnetic material, the control winding being connected across a source of variable voltage to alter the currcnt flow through the control winding and to thereby adjust the fiux concentration in the cornmon core within a desired range up to a condition of saturation.

The variable voltage sourcc for the control winding involves a full wave rectifier 99 cormected acrcss the secondary 161 of a step-down transformer 103, thc primary Tiil5 cf which like the separately excited generator field circuit, is connectable through the normally open contacts 91 or 93 to the secondary of the step-down transformer S3.

The control Winding 1ectifier 99 is selectably connecitable directly to the control winding through either of two normally open pairs of contacts 14W or 1939; er to the coutrol winding through a resistor 111, a pair of normally open contacts 113 and a pair of normally closed coutacts 115; 01 it may be connected through resistor 111, a resistor 117 in series therewith, a pair of normally closed contacts 139 and a pair cf normally open contacts E21; or a connection may bc established through resistors H1, 117, a resistor 123, a pair of normally closed ccntacts 125, a second pair of normally closcd contacts 127 and either of two parallel connectcd pairs of normally open contacts 129 or 131; or finally a connection may 0e established through resistors 1&1E, 117, 12-3, a resistor 133 in series therewith, a normally open pair of contacts 135 and a normally closed pair of contacts 137. With all resistors 111, Tl17, 123 and 133 in the control winding circuit, the minimurn flux density will prevail and the impedance oifered by the powcr windings will be maximum. Consequently the voltage output of the generator will be a minimum. As such resistors a1e removed, the eurrent through the corrtrol winding increases, thus progressively increasing the flux density to saturation, under wl1ich condition, mauimurn voltage will be derived from the generator.

It will be noted that the control Winding adjustably taps into one 0f a pair of resistors 139, 141 connected in series across the generator armature, to thereby include a portion 143 of such resistor in the control winding circuit. Across this resistor accordingly, there Will be developed a voltage drop due to flow of current therethrough from the generator, and such voltage drop Will be in a direction to oppose o1 buck the voltage drop developed across the selected resistors in the control Winding circuit. This opposing voltage serves t0 limit the maximurn to which the voltage across the control Winding may rise.

A minirnum rcfcrence voltage adjustment for the coutrol win iing is determined by a resistor 145 completing a circuit from thc resistor 133 to the bucking voltage resistor 139 through a compensaing winding 147 011 the core of the magnetic amplifier, aud a compensating adjustrnent resistor 1 -59, both thc compcnsating windiug und cornpcnsating adjustrnent resistor being connectcd in parallel with the generator series ficld Winding 37.

When so connected across ihe generator series field wiuding, the compensating winding will react to changes in voltage drop across the series field Winding and Will function through its eficct on the gencrated voltage ro prevent motor speed frorn dropping as the load 011 the hoist motor increases. In the absence of this winding, an increasc in load 011 die motor Would increase the volt age drop in the generator series ficld winding thereby reduciug the voltage applied to the molar armature, with a resulting lowcring of speed of the motor.

T0 further stabilize operation of the motor, insofar as it may be ellected by e1ratic functioniug of the generator, the generator separately excited field winding 39 is shunted by a circuit including an anti-bunt winding 151 in series With a condenser 1153, und a resistor 3i, such 4 shuut circuit acting as a dampaz field voltage, to thereby prevent irrg.

The separatcly excited field Wincling ci1'cuit oi tl1e motor 1 is normally open by the inclusion of a pair of normally open contacts 157 associatcd with a relay 158 connectcd across one phase of the power lines aud adapted to be closed upon energization oi such relay.

Dynamic braking is provided for by a resistor 159 connected through a pair 0f normaliy closcd contacts 166 acr0ss thc mctor armature. Thus uncler conditions where thc armature is roiatiug in the absence cf applied voltage, or as may happen in the case of a hoist, a load on being lowered, might overhaul and drive the motor, th e mstor will fuuction as a gencrator. The resistor 159 will ihen act as a braking load 0r1 the motor.

In conjuncticn with such dyuarnic brakiug, there 1s mechanically coupled t0 and drivcn by the hoist motor, a permanent magnct typc generator 161, the output of which is connectecl across the separately exclted field Winding 15 of the rn0t0r ihr0ugh a pair of normally closed contacts 162 Whicn are also associated With the last mentioned relay. These normally closed contacts are therefore adapted to be opcned upon energization of such relay, and such opening contacts will cccur simultancously Wiith the clcsing oi the coutacts which placcs tlre field winding in circuit with its associatcd rectifier network for normal excitation.

Thus in the event of powcr failurc, or in the cvent the main source of power is otherwise removed, the resulting de-encrgization 0f the relay 158 will open the field circuit of the rno'ror und apply excitation frcrn the permanent magnet type generator in a direction to enhance die dynamic braking.

The meist motor will furtner be equipped with a SO1G* noid releasable spring actuatcd mechanical brake 165 which, in the absence of power to encrgize the solenoid und overcorne the efiect cf the spring, will brake the motor. The solenoid component of such brake is counectable to the output of a rcctificr 166 of the full wave type, through a pair of normally open contacts 167 in cach lead frorn such solenoid. This particular full Wa ze rectifiar is permanently connccted to or1e phasc of the alternating current power supply prcferably ihrough a transformer 168 of the step-down type. Such brake Will assist the dyuamic braking, but failure of such brakc Will mcrely result in increased dynamic braking, duc t0 the increased speed cf the rnctor rcsulting from such failure.

As an added prote-ction, an anti-pluggiug relay 169 is connected across thc motor armature and controls a pair of normally oper1 contacts 17%. The relay is such as releases its contacts when the voltage imprcssed (h-2112 on drops to a precleterrnined value, whereuy the relay can hold a circuit until such lowcr voltage is reached.

As thus far describcd, holst loads arc handlcd by a dircct current motor whose arrnature voltagc is derivecl from a direct current generator, which in turn is mechanically driven by a three phase drive motor energized from a three hase alternating currcnt line. Through generator voltage control as obtainable with a magnetic arnplifier, the speed cf the motor is capable of being varied from its base speed down to approximately 8% of its base speed, while by rneans of ficld weakening as obtainable by sequential inclusion cf resistors in the separately excited field circuit of tl1e motor, die speed cf the motor is capable of being increased upwardly frorn its base speed t0 a value of the oraler of 400% base spced. Such maximum speecl may bs optionally controllcd by the degree t0 which the ficld is permitted to be weakenecl.

Thc foregoing equiprncnt constitutes thc power side 0f the hoist system of the present invention, as distinguished from the control systems. The circuits involved are normally disconnectecl from tha main ower lines by normally open relay contacts 173.

to sudden changes in the tne amplifier from bunt- Power for tl1e conirol circuits is obtainecl through a step-down transformer 175 from a single hase of the main power lines. A start-stop switch arrangement in one of the leacls from this transformer and involving a normally closed stop switch 177 and a normally open sta1t switch 179 detennines when power is made available to tl1e control circuits, Which are suppliecl from a pair of leads 131 and 183.

Connected between the control power leads, chrough two pairs of normally closed contacts 135 .and 187 associated With overload relays 189 and 191 respectively, in the lines to the alternating current motor 35, is a motor start-relay 193, which is adapted to be energized upon the closing of the statt switch l79. This sta1ting relay, when energized, closes normally open contacts 173 in the power lines to the power equipment.

Also associated With the motor starting relay, is a pair of normally open contacts 197 which are connected across the contacts cf the statt switch and funetion as a holding cireuit upon release of the start switch.

Also connectable between the control power leads, through a pair of normally closed contacts 199, a pair of normally open contacts 2M and a second pair of normally closed contacts 203, is an under-voltage relay 205 which controls a pair of normally open contacts 267 in one of tl1e control power leads 181. This leaves all the remaining control eircuits which control the aetual handling f loads, depenclent fo1 power, upon the preliminary energization 013 this relay 2ll5. T bis relay on the other band, cannot be energized until the normally open contacts 261 in circuit therewith are closed.

Such contacts it is noted, are associated witl1 the relay 61 in the separately excited field winding circuit ot the motor, whereby only upon energization o1": t'nis motor field can the associated relay become energized and permit energization of the under-voltage relay 265. The significance cf this lies in the fast that should the motor lose its field, all the load control cireuits become de-energized.

The one pair of normally closed contacts 2ll3, it is noted, 1's associated With an overload relay 269 in the out put circuit of the generator, while the other pair 199 is ass0ciated with the load sensitive relay 17 in the direct current holst motor circuit, whereupon in the event either tl1e gener.ator or the motor are overloaded beycnd a safe limit, tl1e loacl control circuits will become de-energized ihrough opening of the contacts associated with the umlervoltage relay 205.

"Ehe two pairs of normally open contacts 167 in the brake cirouit of the load motor, are associated With a brake relay 221 which is energizable f1'0n1 the control power leacls through a circuit including the relay winding, either one of parallel connected pairs cf normally open contacts 223, 225 respectively, which are in series with another pair of normally open contaets 227; or the brake relay can be energized through an alternative ci1= cuit from the relay winding including one cf. parallel connected pairs of normally open contacts 231, 233 respectively, which are in series With another pair of norxna1ly open contacts 235. Thus before the brake relay can be energized, a circuit through the relay must be completed by way of one of the aforementioned alternative paths.

Tl1e dynamio bral ing contacts 160 in the circuit across the load motor armature, are inclucled in a dynamic braking relay 237 which is connectable between the comtrol power leacis through either of two parallel conneeted pai1s of normally open contacts 239, 241 respectively. Tims energization cf this dynamic braking relay, which woulcl aerve to open the normally closed contacts 160 thereof, can only occur 011 closing of either of the parallel oonnected pairs 01" contacts in circuit With this relay.

Tl1e normally open pairs of contacts 41 and 49, Wl1ich determine rotation of the motor in the lift direetion, are, 212 previously stated, controllecl by relay 43 which deter- 6 mines the up direction of iift of the motor. This relay is ene1gizable fron1 the control power leads 181, 183 through a circuit including either of two pairs of normab ly open contacts 249, 251 respectively, a pair of normally closed contacts 253, und the relay winding.

In parallel with the up relay is a hoist control relay 255, whicn when energizecl, Will eifect closing -0f the contacts 91 to the separately excited field of the generator by way of the rectifier 89; also the normally open contacts 227 in the circuit oi the brake relay 221; and also tl1e normally open contacts 239 in the circuit of the dynarnic braking relay 237.

Also counected in parallel With the up relay 43, is an auxiliary relay 257 which, when energizecl, will control the closing of the normally open contacts 31 in the circuit sl1unting the light load current limiting relay 19 in the circuit to the load motor. The last tuee mentioned relays, namely, the up relay 43, the hoist control relay 255 and the auxiliary relay 257, thus cannot be energized until one pai1 cf the parallel connected normally open contacts 249 and 251 is closed.

The two pairs of normally open contacts 45 and 51 in E116 input leads to the 1notor armature, and Which determine t.ne reverse rotation of the motor for lowering of loads, -as previously stated, are controlled by tl1e down relay 47. This relay is connectable for energization, -between the control power leads, tl1rough eitner of two parallel connectable pairs of normally open conzacts 259, 261 respectively, a pair of normally closed contacts 263 and tlze relay Winding.

'I"ne normally closed contacts 263 in tl e down relay circuit are controlled by the up relay 43, whereas t'ne normally closed contaets 253 in the up relay circuit are eontrolled by tl1e down relay 47. Thus when the up" relay is energized for a lifting operation of lhe holst, it will open tl1e circuit to the down relay and locl 0ut this latter relay while tne lifting operation is in process. Conversely, while a lowering operation is in process, the up relay cannot be energizecl.

In parallel Wi1h the down 1'elay is a Clown eontrol relay 265 corresponding in the lowering operation of a load, to the funetion 013 the holst control relay 255 during a lifting operation, in that it controls the closing 015 the normally open contacts 235 in the braking relay circuit, the closing of the normally open pair of contacis 241 which parallel tl1e hoist control relay contacts 239 in the circuit of tl1e dynamic braking relay 2.557, and the closing cf the normally open contacts 93 paralleling the holst eontrol relay contacts 91 in the circuit to the separately excited Held cf die generator.

Each of these rela'ys, 255 and 265, has an additional normally open pair of contaets 267, 269 respeetively, in series With the normally open contacts of the antiplugging relay 169. An anti-plugging eircuit is completed from control power lead 183 through parallel CO1!- necteci relays 43, 255, 257, the normally closed contacts 253 of relay 47, the normally open contacts 267 0f relay 255 and the normally open contacts 179 0f tne antiplugging relay 169. A sirnilar anti-plugging circuit is completecl from the control power lead 123 through parallel connected relays l'7, 265, the normally closed gentacts 263 of relay 255, the normally open contaets 269 of relay 265, and the normally open contacts 17'0 of the anti-plugging relay 169.

Tl1e functions of controlling the lifting ancl lowering cf loads, are assigned to a pair of controllers 277, 279, the first for heavy load operation within the speed range from the base speed of the load motor to a 1ower speed of the order cf 8% of base speed, while the oth@r Controller serves for light load operation within a speed range extending up to approxirnately 400% oft base speed in the present system, overlapping to a certain extent the lower speed range covered by the heavy luad opera; tion.

Bach of the Controllers involves two se1s of sequem 7 tlally engageable swltch contacts 231, 283 respectively, the one set for the control cf liftlng operatlons am: ti1e other set for the control of lowerlng operations, Wh1ch ol? oourse requlres a reverse rotatlon of the load motor.

Conslderlng the heavy load controller, lt has assoc1ated wlth lt, a first speed determlnlng relay 287. Thls relwy ls connectable in a clrcult between the oontrol power leads whlcn clrcult by-passes the controller contacts. Such circuit inclucles a normally closed palr of contacts elther of two parallel conneotecl palrs of normally open oontaots 291, 293 respectively, the relay Wludiug and, in oommon Wlth the brake relay circuit, the network of normally open contaets 223, 225, 227; 23l, 233 ancl 235.

Nothing happens in connectlon Wlth thls relay 287, however, untll the controller is operated to brldge lt first palr cf oontacts 295. Thls closes a circult through a heavy load holst control relay 297 includlng a mrmally closed palr f lnterlocl; contacts 239, a seoond palr of normally closed contacts 299, the relay windlng, anal a maln holst switch 3ll.

Energization 05 the main load holst control relay 297 directly eloses one palr of the normally open cc-ntaets 225 in the holst brake relay clroult, leavlng the Oi'l normally open palr of eontacts 227 yet be closed before the brake relay clrcult can oe completed. Slmultaneously, the maln load holst control relay 297 also closes a pal1 of contacts 249 in the clrcult to the parallel con nected up relay 43, the holst control relay 255, and the auxlliary relay 257.

Also, the mein load holst control relay 297 closes one of the pairs of contaots 291 in the first speed relay clrcult, to place thls relay in condltlon t0 he energlzed sirnub taneously wlth the holst brake relay 221, when the remainlng pair of open contact s 227 cornmon to the circuits of these relays ls closed. Thls remalning palr of contacts ls closed upon energlzatlon 015 the holst control relay 255, whereupon tne holst brake 1elay Will close its assoclated contaets 167 to energize the solenold comtrolled brake 015 the motor, to hold the Same in released conditlon.

The first speed relay 287, upon lt becomlng energlzed, will close the contacts 135 in the control Wlndlng clrcult to thereby place mlnlmum reference voltage aeross the control Windlng 97. Thls circult may be tracecl frorn the negative side of the rectlfier 99 through the ortion 143 ol reslstor 139, the control windlng, normally closed C011- tacts 137, normally open contacts 135, resistor 133, reslstor 123, reslstor lll.7, and resistor 1Ill. Thls results in minimum excltatlon to the separately exclted field of the generator, whereupon the motor armature Will receive the mlnlh1um voltage from the generator.

Operating the controller to bridge the second palr of contacts 3tl3, serves to energlze a second speed relay 3%5 through a clrcult includlng the normally closed pair of lnterlock contacts 239, the 1'e1ay Wlndlng, and the now closed pairs of contacts 225 and 227, in comrnon Wltl1 the circult through the holst brake relay. The resulting energlzatlon cf the second speecl relay serves to open its normally closed contacts l37 located in the coutrol Wlnding clrcult and slmultaneously therewlth close its normally open contacts 129 to complete a olrouit frorn the control Windlng through contacts l29, normally closed contacts 127, normally closed contacts 125, reslstor 123, reslstor 111, to thereby increase the voltage across the control wincling, by the v0ltage drop through the resis t0r ll33.

Thls results in an increase in the current flow through the control wlndlng, whlch in turn increases tl1e excltatlon of the generator fielcl, wlth a resultln increase ln the generated voltage applled to the lo-ad motor. The motor ls now operating at a hlgher speed than the mln imum speed determlned by the first speed relay Closlng of the thlrd palr of coutacts 397 of the con troller, serves to energlze the thlrcl speed relay in a manuer simllar to tl1e others by conhecting it in parallel therewlth. Energlzatlon of the thlrd speed relay will open cc-ntacts 127 in the control wlndlng clroult and at the same tlme, close normally open contacts T121 t0 further inorease the voltage in the control Wlndlng clrcults by an amount equal to tl1e voltage clr0p aeross the reslstor As in the prevlous lnstances, the generator fielcl excltatlon Will be lncreased, resultlng in an lncrease in generator voltage and a correspondlng lnerease in the speed of the load motor.

Closlng of the fourth palr of contacts 311 Will energlze the fourth speerl relay 33l3, whlch in turn will open Contacts 119 and close contaels 113 to further lncrease the voltage in the eontrol wlndiag clrcult, by an amount equlvalent to the voltage drop tl1rough the reslstor 1l7, thus resultlng ln a further lnerease in speed of the motor.

Maximum speed of the motor for heavy loads, equlvalent in thls case to the base speed of the motor, ls obtalned by connecting the fifth speed relay 315 in parallel wlth the prevlous speed determlnlng relays, through the brldging of a fifth palr of contacts 317 in the controller. Energlzatlon of thls relay, places maxlmum voltage across the control winding, by openlng contacts 115 and closlng contacts 1%7. Thls enables the generator to apply rated voltage t0 tl1e motor armature and cause the motor to run at base speed.

It rnay be noted at thls polnt, the motor speed was controlled entlrely through alterlng -the voltage appllecl t0 the motor armature, frorn vaue substantlally less than ratecl voltage to its rated voltage, and that throughout thls procedure, the resistors 67, 69 and 71 were shuntecl out of the motor field clrcult.

Deceleratlon during liftlng, ls accornpllshecl by a reversal of tl1e proeedure just descrlbed in connectlon wlth the operatlon cf the controller, durlng whlch the coutroller may be reversel3 operated back to its off position, at whlch tlrne, regenerative braking sets in, lf the motor, at the moment ls exceedlng fi1st speed. A signlficant thlng happens, however, durlng the course of such deceleration, clue to the presence cf the antl-plugglng relay clrcult in tl1e syste-m. As prevlously lndlcated, the anti-plugglng relay 169 ls deslgned to open at a low voltage, whlch may be equivalent t0 that voltage applled to the motor frorn the geuerator at the first speed posltlon of the controller. Thls means that the contacts associated Wlth the anti-plugging relay Wlll remaln elosed untll such voltage ls reached during regenerative braklng.

It will be recalled in thls oonnectlon, that the rnain holst control relay 297 was instrumental in lnitially effeotlug energizatlon of the holst coutrol relay 255 and the auxlllary relay 257 in parallel therewlth, but now, due to the presence of the antl-plugging relay circult, the holst control relay and the auxlliary relay do not become cle-energlzed upon the de-energlzatlon of the mein holst control relay, but will rernaln energlzed untll the voltage generated by the n1otor, whlch ls now aetlng as a generator, drops down to the aforementloned value at whlch the antl-plugglng relay will open its contacts.

The Signlficance of tl1ls lies in the fast that a suclden reversal of the controller Will prevent appllcatlon of reverse voltage across the motor arrnature and a comsequent fast appllcatlon of the spring actuated brake, and Will eilect a gradual deoeleratlon of the motor armature and the load whlch ls belng llfted at the tlme and the mechanlcal brake will n0t be applled uutll the relatlonal speed of t'he motor has cl1oppcid to a value sufficlently 10W to permlt mechanlcal braklng wlthout shock to the system.

In lowerlng the loacl, in the heavy load operating cycle, the sec0nd set of contaots 283 of the heavy load eontroller is employecl. In thls connectle-n, lt ls noted that the speed control is exercisecl lhreugh the sarne relays as in llftlng the load, and the first spe-ad relay 287 bears the same relationshlp to tl1e secoud set o1 lowerlng contacts as lt does t0 the first set 0r holstlng contaets, in that its olrcuit ls completed upen brldglng the first pair of coutaets 319 of the seconcl set, whieh eauses the energizatiou of a heavy load lowering control relay 321 through a clrcult inclucllng the normally closed lnterlocklng con tacts .289, a second palr of normally closed contacts 323 and the relay wlnding.

The normally closecl contacts 323 are assoclatecl With the heavy load holst control relay 297 in the llft circuit, whicl1 when energlzed, opens these normally closed Contacts and locks out the lowerlng clrcults.

Llkewlse, the heavy loz-1d lowerlng control relay 321 lncludes the normally closed contacts 229 in the circuit of the main hoist control relay, and consequently, when the lowerlng circuits are being utlllzed, the llfting clrcuits will be locked out by reason of the opening of the latter contacts.

When the heavy load lowering control -relay 321 is energized, lt not only locks out the lifting circuits as mentloned, but slmultaneously therewith, closes the associated normally open contacts 293 in the circult of the first speecl relay. Also, the heavy load lowerlng control relay closes one pair of contacts 233 which are common to the l1oist brake relay clrcult and the clrcuit of the first speed relay. In addltion, the relay 321 brings about energizatlon -of the down relay 47 and the down comtrol relay 265 through closing of the contacts 259 in the clrcuits of these relays. The down relay, when energized, closes the contacts 45 and 51 whlch determine the lowering dlrectlon of rotation of the load motor.

The normally closed cntacts 263 in the circuit to the down relay are opened wl1en the up relay ls energlzed, thus locklng out the down relay clrcult, and lil e- Wlse, the normally closed contacts 253 in the clrcult to the up relay, are openecl when the down relay is energlzed, thus locklng out the up relay circuit, as Well as the circults through the holst control relay 255 and the auxlllary relay 257 which are in parallel with the up relay.

The down control relay 255 closes the contacts 235 to complete a clrcuit through the brake relay 221 and the first speed relay 287. It also, closes the normally open contacts 269 in serles with'the anti-plugging relay coutacts l7ll to provide an antl-plugging circult for malntaining the down control relay energized until the motor speed, during regenerative braklng, drops to a value comparable to the first speed, as determlned by the first speed relay. Until the motor drops to this 10W speed therefor, the down control relay Will malntaln clrcults through the holst brake relay and the dynarnlc braking relay, whereby -regenerative, braking will contlnue until this lower speed ls reachecl, and the spring actuated mechanical brake 011 the motor will be l1eld out of engagemenc and released only when the 1notor speed has dropped t0 such 10W value.

Upon brlclglng the second pair of contacts 325 in the lowerlng set of the heavy load controller, a circuit is completed through the second speed relay 365, such circuit inoluding the normally closed interlock contacts 2il9 the relay wlndlng, -and the contacts in common Wlth the holst brake relay clrcult. This relay then will increase the lowerlng speed -to the second stage, by increaslng the current through the control wlncling of the magnetlc ampllller. In like manner, the lowering speed may be successively lncreased through three additional stages, lf deslred, by sequentially bridglng sucoessive palrs of comtacts 32'7', 329 and 331.

By reversing the operatlon of the controller, the lowerlog speed may be reduced, and brought to a stop, the mechanlcal brake then functlonlng to hold the motor and load at a standstlll.

Now referring to the llght load controller 279, lt has associated With lt, a first speed relay 351, whlch is counectable hetween the control power leads 181, 183 in a circuit includlng a pair of normally closecl contacts 353, a parallel arrangement of two pairs of normally open contacts 355, 357, the relay windlng, and the arrangement of normally open contacts 223, 225, 227; 231, 233, 235 whlch are comrnon to the orake relay circuit and the lll clrcults of the speed relays associated wlth the heavy load controller.

This first speed relay, however, does not become energlzed untll a circuit ls completed through the beforementioned normally open contacts, and thls ls accompllshed through brldglng of the first pair of contacts 359 in the set of contacts 281 employecl for llfting operations. Closing of the first palr of contacts, closes a circuit through a llght load holst control relay 361 through the normally elosed lnterlock contacts 353, a second pair of normally closed contacts 363, the relay wlndlng, and the holst limit switch 301.

This relay when tl1us energlzed, functlons along the llnes of the heavy load holst control relay 297, in that lt closes the normally open contacts 223, common to the brake relay -circuit and the speecl relay circuits; lt closes the normally open contacts 251 to complete the clrcul-t through the up relay 43, the holst control relay 255, andthe auxiliary relay 257; and lt closes one of the palrs of normally open contact s 355 in the clrcuit of the first speed relay.

Tims, the light load holst control relay 361 sets up the clrcuit through the brake relay to eflect a wlthdrawal of the mechanlcal brake on the load motor; lt sets up the circuit through the up relay which connects the load motor across the generator for lift rotation; lt completes the clrcuit through the holst control relay 255, Which, among other things, completes the clrcuit to the generator separately excited field, and the magnetlc ampllfier; and further, in additlon to completlng the clrcuit through the dynamic braklng relay, which serves to disconnect the dynamic braklng circuit, lt closes contacts 267 to complete the anti-plugging clrcuit.

The auxilialry relay 257 whlch ls energized along wlth the up relay and the holst control relay, as before, closes its contacts 31 to shunt the llght load current llmit relay 19.

Upon becomlng energlzed, the first speed relay 351 in the light load holstlng cycle, closes the normally open contacts 131 in the control Winding clrcuit, to cause eurrent to flow through the control wlndlng corresponding to the second speed relay of the heavy load holstlng cycle. Thus for light loads, the first speed will be comparable co the second speed of the heavy load llfting cycle, Which ls perm=lsslble in liftlng llghter loads.

Upon closing of the seoond pair of contacts 365 in the light load hoisting cycle, a second speed relay 367 is thereby connected in parallel Wltl1 the first speed relay. This second speed relay also operates on the magnetic ampllfier by closing the normally open contacts 109 to cause maxlrnum voltage 011 the control wlndlng, whlch produces rated speecl of the load motor and corresponds to tl.he 5th or maximum speed in the heavy load lifting cyc e.

T0 thls extent, the lower end of the speecl range for the light load llftlng cycle, overlaps the higher end of the speed range for the heavy load lifting cycle.

Closing of the second palr of contacts also completes a clrcuit tl1rough a time delay relay 365, a palr of normally closed contacts 371l, and those contacts common to the b1ake relay und speed relay circuits,

The tlme delay relay controls a palr of normally open contacts 373 in the circult of a third speed relay 375 whlch is connectecl in parallel With the tlme delay relay, when said time delay relay contacts are closed. It accordlngly sets up the thlrd speed relay circuit to be closecl upon brldging the third set of contacts 379.

The thlrd speed relay when energized, among other things, opens the normally closed contacts whlch shunt the field res-lstor 67 in the circuit of the separately excltecl field of the load motor. The lnclusion of this reslstor in the fielcl clrcult, serves to weaken the field and bring about an increase in the speed of the load motor, over and above that resulting in the energizatlon of the second speed relay.

The normally closecl contacts 571 in the thlrd speed ll. relay circuit, are controlled by the light load current limit relay 19 of the motor circuit. By selecting the resistor 29 as to value, sufiicient cf the lad current can be made to pass through the light load cu1renc lirnit relay 19 during overloads of the order of say 125% full load, to cause its contacts 371 to open.

When such an overload ocurs, further increase in the lifting speed of tne motor is undesirable. The time delay relay therefore is timed to give the light load current limit relay 19 an opportunity to sense the load condition on second speed, which is the base speed of tne motor, before closing its contacts 373 in the circuit cf the third speecl 1elay 375. lf an overload exists the prior opening of the contacts 371 of the light load eurrent limit relay will render the clcsing of the time delay relay contacts ineflective. During light load lifting, therefore, the maxirnum speed Will be limited t0 the base speed of the motor in the event of an overload.

The Slllllling resistor 29, when connected in circuit, functi0ns additionally to compensate for revrsal in system eificisncy due to direction of operatlon, causing lass load current flow during lowering than during lifting, with a given hook load.

The fourth pair of controller contacts 381 are located in a clrcuit through a fourtn speed relay 383, such circ'uit including the normally closed interlock contacts 353, a normally open pair cf contacts 335 associated with the third speed relay 375, the relay winding, and a second pairs of normally open contacts 387 controlled by the third speed relay and parallsling the normally closed contacts 37ll of the light load current limit relay.

Being that the thlrd speed relay is in an energized condition, the normally open pairs of contacts in the fourth speed relay circuit Will now be closed, anal causa the fourth speed relay to become energized. lt in turn will open its normally closed contacts 83 Which shunt the resistor 69 in tl1e circuit cf the mot0r field, thereby cutting this resistor into tl1e circuit to further weaken tne motor field and bring about increase in the speed of. the motor.

Closing of the fifth pair of contacts 339 f0r light load lifting, cornpletes a circuit through a fifth speed relay 391, which circuit includes the normally closed interlock contacts 353, a pair of normally open contacts 393 associated With the previously energized fourth speed 1ela the relay Winding, and the normally open but now closed contacts 337 of the third speed relay, such contacts as previously pointed out, being in parallel With the normally close contacts 371 of the lignt load current limit relay 19.

The fifth speed relay when energizecl, will open coutacts 85 wl1ich shunt the resistor 71 in the motor field circuit, tl1us fincluding such resistor, which serves to furtl1er weal .en the motor fisld and thus bring about an additional increase in the speed of tl1e motor. At this point the load motor is running at maximum speed which rnay b-e 0f tlze order of 400% or more tin1es its base speed.

By reversing tne sequence 0f operations in the hoist cycle cf the light load controller, the speed of the mot0r may be cllminished anal brought to a halt when the comtroller is acljustecl to its 0ll position.

For a lowering operation on li ht loads, tl1e sarne speed relays are utilized, laut in conjunction with the lowering sei cf coniacts 283. The circuit through the first speed relay remains substantially unchanged except for the C108- ing of normally open cantacts 357 in lieu of contacts 355, and the closing of normally open contacts 231 and 235 in lieu cf contacts 223 and 227. The two rn intioned pai1s of normally open contacts 357 and 231 a1e directly associated Witn a light load lowering control relay 395 cannected in circuit between tl1e control power leads, auch circuit including tne normally closecl interlock contacts .353, a pair of normally closed contacts 397 and the relay winding. T s relay 335 is energized by the brldging 05 tbe first pair of c0ntacts 598.

Tl1e n0rmally closed contacts it Will be noted, are

associatsd Witn tl1e light load hoisc cc-ntrol relay 361 while tl1e normally closecl contacts 363 in the circuit of the light load l1oist con;rol relay 361 an: associaied with tne ligl1t lcad lowering control relay 395. establishes a lockout feature, whereby when the holst circuits a1e being utilized, the lowering ci1cuits Will b: l0cked out, and conversely, when the lowering circuits am being utilized, tne lifing circuits Will be loclzed out.

The light load lowering control relay 355 performs functlons sirnilar to t'ne light load holst concrol relay 351. lt closes a pair cf normally open contacts 231 in that porti0n cf tne system common to the brake relay circuit and the speed relay circuits; it cl0ses a pair of contacts 261 in tne circuit of the down relay 47 and the down control relay 265, tl1e down relay in turn closing the contacts 45, 51 in the motor circuit t0 establish rotazion in the lowerlng direction, Wl1ile the down control relay in turn closes ehe contacts 235 t0 complete the circuit through the brak'e relay and. partially complete tl1e circuit through tl1e first' speed relay 351, which circuit is completed upon closing the ncrnmlly c-pen contacts 357 in said circuit, which conlacts are also associated With tl1e light load lowering control relay 395.

Thus energization of tnis latter relay, in terms of the holst equipment, connects the motor for proper direction of rotation, withdraws the mechanical brake from the motor, opens the dynamic braking circuit, and establishes rotation of the motor at a minimum light load speed comparable to the second speed for heavy load operation.

In terms of the control circuits, the Clown relay 47 is energized and opens contacts 253 in the circuits of the holst control relay 255, the up relay 43 and the auxiliary relay 257, t0 preclude energization of any cf these relays.

The opening cf the circuit to the auxiliary relay .257, leaves the shunt circuit around the light load current limit relay 19 open, tl1us exposing the light load current limit relay to full load current in the m0tor circuit during the lowering cycle.

Ordinarily, the loads will be sufilcient to mechanically drive the motor during lowering. F01 very light loads, insufi1cient to mechanically drive the motor, tl1e m0tor will 'oe electrically driven and will accordingly function as a motor.

For loads, sufiiciently heavy t0 mechanically drive the motor, tl1e motor will then function as a generator in cum driving the direct current generator as a motor. This unit mechanically connected to t"ne dr.ive motor Will funcion as an induction generator pumping the power generated into the main power system.

Bridging cf th.e second pair 0f contacts 399 in the lowering cycles cf the light load controller, closes a circuit through the second speed relay 367, as well as a circuit through the time delay relay 359 whose circuit includes the normally closed contacts 371 cf the light load current relay 19 and the normally open contacts 387 of the third speed relay which contacts are in parallel with the normally closed contacts 371.

The time delay relay delays the closing of its associated normally open contacts 373 in tne third speed relay circuit, f01' a time su1'ficient to permit the lignt load current limlt relay 19 to respond to any cverloads which may exist at the moment in the load motor circuit Shoulcl such an overload exist, tl1e llght load current limit relay contacts 371 Will open befo1e the third speed relay circuit can be closed through the time delay -relay contacts. Thus, further increase in speed of the motor above second speed will be precluded during a light load lowering 0peration, shonld an overload current exist.

On the othar band, if' no overload current exists, the tlme delayed contacts 373 will close and complete the circuit through the tl1ird speed relay except for the bridging cf a third pair of contacns 401. This tl1ird speed relay will not only cut in resistance 67 to effect an increase in speed of tl1e motor, laut Will at tne same time, close Lhe normally open contacts 385, 387 in the fourth speed relay circuit, to set up this circuit fr operation When the fourth set of contacts 403 cf the 1owering set 283 is closed.

The resulting energization of the fourth speed relay will increase the speed cf the load motor through inclusion of the resistor 69 in the field circuit. At the same time, the fourth speed relay will close the norrnaily open contacts 393 in the circuit cf the fifth speed relay 391 to set this relay up for operati0n when the controller is operated to bridge the last pair of contacts 495 of the 10W- ering cycle. This fifth speed relay then will further increase the motor speed through inclusion cf the resistor 71 in the motor field circuit.

Deceleration of the load being lowered is accornplished through reverse sequence of operation 015 the controller lowering contacts, until the oft position is reached, when the motor and load may be held a1: a fixed position by the mechanical brake which, in the meantime, has been permitted to effect its braking fimction.

During a hoisting operation on light loads where motor speed is increased through the inclusion of resistors into the field circuit cf the motor, the -sudden inclusion of resistors would normally tend to produce a sharp increase in motor armature current, which would result in jerky operation of the hoist, not to mention the efiect of the sudden changes in 1oad produced thereby on the hoist equipment.

T0 alleviate this condition and bring about a smoother operation, the field accelerating relay 23 is employed. This relay as previously described, is a vibrating type relay, utilizing a double coil, the one coil 21 being comnected in the motor armature circuit, while the other coil 73 is included in the field circuit of the motor.

This vibrating type relay controls a pair of contacts 407 which shunt the resistors 67, 69 and 71 in the field circuit of the load motor. The vibrating contacts alternately in. sert and remove such resistors from the field circuit as are being utilized, thereby causing the acceleration dun'ng hoisting to be gradual. During lowering of a load, the relay is rendered imperative due to the fact that the windings thereof are in bucking relationship to one another.

During the lowering of a load, the rate of deceleration due to increased field strength dnring regenerative lowering, also causes excessive motor armature current, resulting in operation which may be somewhat jerky, and to alleviate this condition, the vibrating -relay 27 is Uti- 1ized.

This relay also employs two windings, one of which 25 as previously indicated, is connected in the motor armature circuit, while the other 409, is connected across the separately excited field circuit of the motor. This relay controlg the vibration cf the normally closed cantacts 79 which shunt the resistor 65 in the field circuit of the motor. The vibration cf these contacts during a lowering operation will serve to smooth out the rate of deceleration as the resistors which control field weakening are sequentially shunted out 01: the circuit. During hoisting, this relay becomes inefi'ective inasrnuch as the windings of the relay will be bucking each other due to a reversal cf the current in the motor circuit.

The -system described above has speed-load characteristics which when plotted, produce substantially flat speed curves which drop but slightly, of the order cf 5% for the light Ioad range, from no load to approximately 135% fu1l load, and lass than 5% for the heavy 1oad range. This means, that for any speed setting of the load motor, either hoisting er lowering throughout both the heavy and 1ight load speed ranges, the speed will remain substantially unafiected by variations in load.

The field of use cf the system is not limited to any one particular type of hoist equipment, but may be employed in cranes, trolley and bridge type of hoist equipment, or in other known types.

From the foregoing description of our invention in its preferred form, it will be apparent that the Same fulfills all the objects of the invention, and whi1e We have illustrated and described the same in detail, it will be apparent that the system is subject to alteration and modifications without departing from the underlying principles involveci. We accordingly do not desire to be limited in our protestion to the specific details thus illustrated and described except as may be necessitated by the appended claims.

We claim:

1. A hoist systexn comprising a hoist motor and hoist mechanism drive-connected thereto, said hoist mechanism including common rneans for connecting and lifting a light 0r heavy physical load; manually controlled means :for altering the speed of said hoist motor for lifting heavy physical loads, Within a predetermined speed range; manually controlled means independent of said first manual1y controlled means for altering, the speed of said hoist motor for lifting light physical loads, Within a speed range extending above said first speed range; and means respon sive to utilization of one of said speed altering means f01' rendering impotent, the other of said speed altering means.

2. A hoist comprising a hoist motor of a rated base speed and hoist mechanism drive-connected the1eto, said hoist mechansim including cornmon means for connecting and lifting a light 01' heavy physical load; manually com- 1;rolled rneans for altering the speed of said hoist motor for lifting heavy physical loads within a speed range extending below its base speed; manually controlled means independent of said first manually controlled means for altering the speed of said hoist motor f01' lifting light physical loads within a speed range extending above its base speed but overlapping the first speed range; and means responsive to utilization of one of said speed altering means for rendering impotent, the other of said speed altering means.

3. A hoist system comprising a hoist motor of a rated base speed and hoist mechansim drive-connected thereto, said hoist mechanism including common means for cannecting and lifting a light or heavy physical ioad; rneans for a'1tering the speed of said hoist motor for lifting heavy physical loads within a speed range exten-ding below its base speed; means for altering the speed of said hoist motor for lifting light physical loads within a speed range extending above its base speed; means responsive to an overload While operating said hoist motor to 1ift a heavy load at a speed within the heavy load speed range, for shutting down said system, and means responsive to an overload While operating said hoist motor to lift a light load within said light load speed range, f01' precluding an increase in speed of said motor beyond an intermediate value of speed Within said Iight load speed range.

4. A hoist system comprising a hoist motor of a rated base speed and hoist mechanism drive-connected thereto, said hoist mechanism including common means for comnecting and lifting a light or heavy physical load; means for altering the speed of said hoist motor f01 lifting heavy physical loads Within a speed range extending below its base speed; rneans for altering the speed of said hoist motor f0r lifting light physical loads within a speed range extending above its base speed; means responsive to Utilization of one of said speed altering means for rendering impotent, the other of said speed altering means; means responsive to an overload While operating said hoist motor to lift a heavy load at a speed within the heavy load speed range, for shutting down said systern; and means responsive to an overload While operating said hoist n1otor to lift a light load within said light load speed range, for precluding an increase in speed of said motor beyond an intermediate value cf speed Within said 1ight load speed range.

5. A hoist system comprising a hoist motor having an armature and a field winding; hoist mechanism coupled to said motor for lifting a physical load means including said hoist motor for accelerating a heavy physical load within a predetermined range of speed; means for accelerating a lighter physical 1oad within a predetermined higher range of speed; and means responsive to an over 1oad current ihrough said motor during handling of the lighter 102d only, for precluding acceleration of said lighter load above a predetermined intarmediate speed within said higher range cf speed.

Referemes Ciied in the fi1e of this patent UNITED STATES PATENTS Lindquist j'uly 11, 1916 Simmon et a1. Iu1y 17, 1917 16 Henderson et a1 Aug. 28, Riecke Oct. 22, Kuhn Oct. 10, Whittaker Apr. 17, Ogden et a1. Inne 23 Moore Oct. 21, Burgy Jan. 14, Helot Nov. 24, Fisher Das. 22, Hunt Nov. 1, Herchenroeder et a1 Mar. 27, Krabbe et a1. Jan. 15, 

1. A HOIST SYSTEM COMPRISING A HOIST MOTOR AND HOIST MECHANISM DRIVE-CONNECTED THERETO, SAID HOIST MECHANISM INCLUDING COMMON MEANS FOR CONNECTING AND LIFTING A LIGHT OR HEAVY PHYSICAL LOAD; MANUALLY CONTROLLED MEANS FOR ALTERING THE SPEED OF SAID HOIST MOTOR FOR LIFTING HEAVY PHYSICAL LOADS, WITHIN A PREDETERMINED SPEED RANGE; MANUALLY CONTROLLED MEANS INDEPENDENT OF SAID FIRST MANUALLY CONTROLLED MEANS FOR ALTERING THE SPEED OF SAID HOIST MOTOR FOR LIFTING LIGHT PHYSICAL LOADS, WITHIN A SPEED RANGE EXTENDING ABOVE SAID FIRST SPEED RANGE; AND MEANS RESPONSIVE TO UTILIZATION OF ONE OF SAID SPEED ALTERING MEANS FOR RENDERING IMPOTENT, THE OTHER OF SAID SPEED ALTERING MEANS. 